Multi-station document inserting systems generally include a plurality of various stations that are configured for specific applications. Typically, such inserting systems, also known as console inserting machines, are manufactured to perform operations customized for a particular customer. Such machines are known in the art and are generally used by organizations, which produce a large volume of mailings where the content of each mail piece may vary.
For instance, inserter systems are used by organizations such as banks, insurance companies and utility companies for producing a large volume of specific mailings where the contents of each mail item are directed to a particular addressee. Additionally, other organizations, such as direct mailers, use inserts for producing a large volume of generic mailings where the contents of each mail item are substantially identical for each addressee. Examples of such inserter systems are the 8 series and 9 series inserter systems available from Pitney Bowes, Inc. of Stamford, Conn.
In many respects the typical inserter system resembles a manufacturing assembly line. Sheets and other raw materials (other sheets, enclosures, and envelopes) enter the inserter system as inputs. Then, a plurality of different modules or workstations in the inserter system work cooperatively to process the sheets until a finished mailpiece is produced. The exact configuration of each inserter system depends upon the needs of each particular customer or installation.
For example, a typical inserter system includes a plurality of serially arranged stations including a sheet feeding station, a folding station, a plurality of insert feeder stations, an envelope feeder and insertion station and an output station for collecting the assembled mailpieces. As is conventional, the sheet feeder feeds one or a plurality of sheets to an accumulating station, which collects the fed sheets into a predefined collation packet. This collation is then preferably advanced to a folding station for folding the collation. Thereafter, the serially arranged insert feeder stations sequentially feed the necessary documents onto a transport deck at each insert station as the folded collation arrives at the respective station to form a precisely collated stack of documents which is transported to the envelope feeder-insert station where the stack is inserted into the envelope. The finished envelope is then conveyed to an output station for distribution into the mail stream. A typical modem inserter system also includes a control system to synchronize the operation of the overall inserter system to ensure that the mailpieces are properly assembled.
Aside from reliability, one of the most important features of a modem inserter system is speed. Speed is defined as how many mailpieces can be assembled in a given time period. For instance it is known to process up to twelve thousand (12,000) mailpieces each hour, where each mailpiece consists of a three (3) page folded collation and at least one insert. However, speeds much higher than his rate are extremely difficult because current sheet feeders are unable to reliably feed sheets at such high speeds.
Such a known sheet feeder can be found in U.S. Pat. Nos. 4,579,330 and 4,787,619, both of which are assigned to Mathias Bauerle GmbH of the Federal Republic of Germany. In brief, this is a pneumatic sheet feeder that removes individual sheets from a stack. The sheet feeder includes a table having a surface for supporting a stack of sheets. A pair of parallel guide rails are provided on the table and with facing surfaces so that the stack is confined between the guide rails for movement in a feed direction across the table. Blast nozzles are provided in the guide rails for blowing air against the stack to form an air cushion between lower sheets of the stack. A suction cylinder is rotatably mounted to the table and includes a suction chamber therein for receiving a vacuum. Radial openings in the suction chamber cause a suction induced adhesion of a leading edge of a lowermost feed in the stack so that with rotation of the cylinder, the lowermost sheet is fed in the feed direction away from the rest of the stack.
In use, this sheet feeder has proven reliably when operating at speeds up to approximately 35,000 sheets per hour. The aforementioned sheet feeder is unable to operate at speeds greater than this rate because of its limited speed in the vacuum valve system and in the velocity of its outer feed drum.
Thus, it is an object of the present invention to provide an improved sheet feeder that operates to reliably feed sheets at speeds in excess of that which is capable by the above described prior art sheet feeder.